Operator-language Feynman rules for driven-dissipative quantum systems: from mean field to non-Gaussian photon correlations
Abstract
We construct Feynman rules for Lindblad master equations in the operator language of quantum optics: a fixed algebra of elementary operator moves and closed-form propagators for perturbation theory about an exactly solvable, in most cases Gaussian, generator. The expansion separates into a kinematic part (the shift algebra on the Wick-ordered eigenoperators Omn=:(c†)m cn:, from which the vertex table for a specified interaction is assembled) and a dynamical part that enters only through the resolvent of the unperturbed generator, diagonal and additive for any stable, diagonalizable Gaussian L0, including thermal and squeezed reservoirs and correlated decay, and equally available for a two-level emitter, driven or undriven. In the driven Kerr cavity the loop expansion is the semiclassical expansion and the series is asymptotic. In a strongly driven two-level atom, dressed lines replace a series of finite radius by one accurate deep into saturation, one line per Mollow component. For Kerr rings and chains the cost is polynomial in the number of sites at fixed perturbative order. On a three-site ring the diagrams recover the non-Gaussian part of the three-photon correlation that the Gaussian cumulant closure lacks; carried to tenth order they give the smallest g(3) error of the methods compared for U≤0.25κ at a cost below that of a fourth-order closure, and third- and fourth-order closures are more accurate at moderate coupling. The same rules, extended to the counting-field-tilted generator, give the photon-counting cumulants of a disordered eight-site chain beyond direct diagonalization; quantum-jump trajectories at three couplings agree with them to within $1.6$ standard errors, within one at the strongest coupling, where they place the third cumulant six standard errors above the Gaussian value.
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BibTeX
@misc{ehlers2026operatorlanguage,
title = {{Operator-language Feynman rules for driven-dissipative quantum systems: from mean field to non-Gaussian photon correlations}},
author = {Peter Ehlers and Phi Hung Nguyen and Daniel Soh},
howpublished = {arXiv},
year = {2026},
month = oct,
doi = {10.48550/arxiv.2610.00667},
eprint = {2610.00667},
archivePrefix = {arXiv},
url = {https://arxiv.org/abs/2610.00667},
note = {CC0},
}
RIS
TY - UNPB
TI - Operator-language Feynman rules for driven-dissipative quantum systems: from mean field to non-Gaussian photon correlations
AU - Peter Ehlers
AU - Phi Hung Nguyen
AU - Daniel Soh
PY - 2026
DA - 2026/10/01
PB - arXiv
DO - 10.48550/arxiv.2610.00667
UR - https://arxiv.org/abs/2610.00667
AB - We construct Feynman rules for Lindblad master equations in the operator language of quantum optics: a fixed algebra of elementary operator moves and closed-form propagators for perturbation theory about an exactly solvable, in most cases Gaussian, generator. The expansion separates into a kinematic part (the shift algebra on the Wick-ordered eigenoperators O_mn=:(c^†)^m c^n:, from which the vertex table for a specified interaction is assembled) and a dynamical part that enters only through the resolvent of the unperturbed generator, diagonal and additive for any stable, diagonalizable Gaussian L_0, including thermal and squeezed reservoirs and correlated decay, and equally available for a two-level emitter, driven or undriven. In the driven Kerr cavity the loop expansion is the semiclassical expansion and the series is asymptotic. In a strongly driven two-level atom, dressed lines replace a series of finite radius by one accurate deep into saturation, one line per Mollow component. For Kerr rings and chains the cost is polynomial in the number of sites at fixed perturbative order. On a three-site ring the diagrams recover the non-Gaussian part of the three-photon correlation that the Gaussian cumulant closure lacks; carried to tenth order they give the smallest g^(3) error of the methods compared for U≤0.25κ at a cost below that of a fourth-order closure, and third- and fourth-order closures are more accurate at moderate coupling. The same rules, extended to the counting-field-tilted generator, give the photon-counting cumulants of a disordered eight-site chain beyond direct diagonalization; quantum-jump trajectories at three couplings agree with them to within $1.6$ standard errors, within one at the strongest coupling, where they place the third cumulant six standard errors above the Gaussian value.
ER -